Just last month, FBI raided former Trump campaign chairman's apartment

At Robert Mueller's behest, quite possibly looking for incriminating material unrelated to Russia or the campaign.

By all accounts, former Trump campaign chairman Paul Manafort has been cooperating with investigators, and has been handing over information they've requested. That should make for a fairly smooth investigation that stays within its supposed parameters.

Fishing expeditions are different matters, though, and independent counsel investigations usually turn into fishing expeditions. They have unlimited time and unlimited budgets, and they feel compelled to find someone to indict so they can justify their existence. And often, the "crimes" they uncover are not even related to the original reason for the investigation.

So why raid Manafort's apartment, as the FBI apparently did in July, when he's already giving you everything you ask for. Because you want more, that's why. If you can find incriminating information on him - even if it's not related to the campaign or the Russia probe - that gives you leverage to put the muscle on him to turn coat and testify against very high-profile targets. Maybe even the president himself.

Federal agents appeared at Paul Manafort’s home without advance warning in the predawn hours of July 26, the day after he met voluntarily with the staff for the Senate Intelligence Committee.

The search warrant was wide-ranging and FBI agents working with special counsel Robert S. Mueller III departed the home with various records. Jason Maloni, a spokesman for Manafort, confirmed that agents executed a warrant at one of the political consultant’s homes and that Manafort cooperated with the search.

Manafort has been voluntarily producing documents to congressional committees investigating Russia’s interference in the 2016 presidential election. The search warrant indicates investigators may have argued to a federal judge they had reason to believe Manafort could not be trusted to turn over all records in response to a grand jury subpoena.

It could also have been intended to send a message to President Trump’s former campaign chairman that he should not expect gentle treatment or legal courtesies from Mueller’s team.

The documents included materials Manafort had already provided to Congress, said people familiar with the search.

“If the FBI wanted the documents, they could just ask [Manafort] and he would have turned them over,” said one adviser close to the White House.

Josh Stueve, spokesman for Mueller, declined to comment, as did Reginald Brown, an attorney for Manafort.

“Mr. Manafort has consistently cooperated with law enforcement and other serious inquiries and did so on this occasion as well,” said Maloni, the spokesman for Manafort.

Mueller has increased legal pressure on Manafort, consolidating under his authority a series of unrelated investigations into various aspects of Manafort’s professional and personal life.

Manafort’s allies fear that Mueller hopes to build a case against Manafort unrelated to the 2016 campaign, in hopes that the former campaign operative would provide information against others in Trump’s inner circle in exchange for lessening his own legal exposure.

Lovely. Mueller is now "consolidating under his authority a series of unrelated investigations into various aspects of Manafort's professional and personal life." In other words, he's targeting Manafort, hoping to compromise him legally in any way he can so he can get him to turn against others Mueller would like to indict. It doesn't matter to Mueller if he nabs Manafort on a matter pertaining to Russia, or an entirely unrelated business contract, or who he may have been sleeping with. As long as he can get him on something, Manafort is put in a precarious position and Mueller is able to offer him a way out only if he helps them nab the bigger fish.

Now I was not born yesterday and I understand that sometimes in criminal investigations, it's necessary for investigators to play hardball. If you know there's a major crime racket operating but legal technicalites are making it hard for you to prove it, then sometimes police or the FBI have to get creative in how they get potential witnesses to cooperate. In general, I don't have a philosophical problem with that. I want the good guys to nab the bad guys. That's more important to me than the technical nuances of how they did it in most cases. I'm not a libertarian.

But what we have here is a gross distortion of that principle at work. Robert Mueller is looking into a notion that was largely created by the media and chatter amongst the political class. There has been a lot of scuttlebutt about so-called collusion, but there is no substantive reason to think it went on, and after a year of various parties looking into it no one has found any evidence.

If you know there are drugs on the street and you're trying to find out who put them there, then you know there's a crime. You just have to find out who's committing it.

No one knows if there was any collusion between the Trump campaign and Russia, and there are a lot of reasons to think there was none. It's entirely possible that there is no underlying crime at all to investigate here.

So Mueller isn't targeting some known crime boss who's very good at protecting himself from prosecution. He's trying to give some substance to a suggestion that may actually have no substance to it whatsoever.

Yet he's been turned loose with a limitless budget and given free reign to go after people for whatever reason, just so he can muscle them into playing ball. Is it really a good idea to empower an investigator to do this sort of thing, when he essentially can't be fired, can't be reined in, and might be doing all of this only to find out there was never any crime in the first place?

And even if he ultimately determines there was no crime, he could still charge people and get convictionsd. Scooter Libby could tell you all about that. So could Caspar Weinberger if he was still alive. Both men were convicted of crimes that arose from independent counsel investigations, even though the investigations found no underlying crime. They were charged with technicalities about notes not turned over, details of phone calls not recalled correctly and so forth. Most of the convictions the result from independent counsel investigations are of this nature. They are process crimes that only arise from the investigation itself.

Clearly, this is Robert Mueller's strategy for bringing down someone in the Trump inner circle: Expand the investigation as much as you have to in order to nab someone for something, anything, and then apply your legal leverage. Did any collusion really take place? Ever? By anyone? Not as far as we can see, but Robert Mueller is going to indict someone because he has to justify his existence somehow. That, not real justice, is what this is all about.